Dynamic myocardial response to exercise in children with transposition of the great arteries post arterial switch operation
Bibliographic record
Abstract
Abstract Funding Acknowledgements Type of funding sources: None. Background The arterial switch operation (ASO) has improved outcomes for patients with transposition of the great arteries (TGA) however the long-term impact on myocardial function and functional reserve during exercise remains poorly described. The aim of this study was to evaluate left (LV), and right ventricular (RV) myocardial response to exercise in children post ASO using semi-supine cycle ergometry stress echocardiography (SSCE). Methods This is a single-center cross-sectional study. Participants prospectively underwent exercise stress echocardiography using a semi-supine bicycle and a stepwise exercise protocol. Systolic (s’) and diastolic (e’) tissue Doppler velocities, as well as myocardial acceleration during isovolumic contraction (IVA) were measured at rest and during exercise at incremental heart rates (HR) in the basal segments of the RV lateral wall, IVS and LV lateral wall. Systolic and diastolic reserve were evaluated by plotting s’ and e’ against HR while contractile reserve was assessed by plotting IVA values against HR which represents the force-frequency relationship (FFR). Results A total of 40 patients with TGA and 29 controls were included. There were no differences between groups in age (14.6 ± 2.9 vs 14.3 ± 3.1 years, p= 0.75), sex (male= 30/40 vs 20/29 p= 0.58), and resting HR (67 ± 12 vs. 71 ± 12 bpm, p = 0.31). Peak HR was lower in the ASO group (142.2 ±12.4 vs 157 ± 12.3 bpm, p< 0.01). At rest, the ASO group showed lower s’ in the RV and IVS (RV s’: 5.7 ± 1.4 vs. 10.2 ± 2.1 cm/s, p <0.001; IVS s’: 4.2 ± 1.3 vs. 6.2 ± 1.8 cm/s, p< 0.001); lower IVA in the IVS and LV (IVS: 1.01 ± 0.37 vs. 1.23 ± 0.4 m/s2, p= 0.03; LV: 0.86 ± 0.32 vs. 1.1 ± 0.4 m/s2, p =0.02), and reduced e’ in all segments. At peak exercise the ASO group showed reduced s’, e’, and IVA in all segments (table1). When plotted against HR, there was blunting of the s’ slope in RV and septal segments while the LV s’ slope was similar between groups. There were no differences in e’ slope when compared to controls (figure 1). The ASO group showed a blunted IVA response to HR in all measured segments compared to controls. Conclusion(s): Our data demonstrate patients post ASO have reduced RV and LV contractile reserve in response to exercise. The etiology and long-term implications of these abnormalities however remains to be described. Abstract Figure. Doppler velocities at baseline and peak Abstract Figure. Dynamic response to exercise
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".